Soap product containing guanidine stearate



Patented Jan. 25, 1949 UNITED. STATES rare-NF 2,459,18 rio's sosrrnonuorrcoN'rAlNmo GUANID'INE' j lSTEARATE Lloyd F. Henderson, Reading, Mass, assignor to Lever Brothers Company, ('fiamliridge, Mass, a

corporation of Maine No Drawing. Application August 4, 1944, "Serial No. 548,142 H This invention relates to a soap product com.

prising guanidine .stearate.

The word soap is used herein to refer to alkali metal salts of the fatty acids and/prrosin acids and mixtures of the same. The expression soap product is used herein to refer to a composition comprising soap as the primary ingre dient but also including small amounts of other ingredients in. admixture with soaps, such as antioxidants, coloring materials, perfumes, water,

3 claims- %1-1 glycerine, and ingredients to modify or enhance It has been discovered in accordance with the i invention that the addition of guanidine stear lte in moderate amounts to ordinary soaps results in a s ap pr du t av n novel and desi able haracteristics, particularly a soap product of improved apparent solubility rate and also increased crutohing, plodding, milling, convertingpr other operations to which the soap is subjected, which would result'in the uniform admixture of the guanidine stearate with soap. Ingredients ordinarily added mayalso be included.

The amount of the guanidine stearate to be, added to the soap may vary from about; to by weight, depending upon the nature of the soap and the properties wanted in the final-prodnot. The use of 5% by weight results in agood effect. In general, amounts above 10% by weight do not appear to improve the properties to such an extent as to justify the use of greater amounts.

One of the novel properties of the soap product containing guanidine stea-rate in accordance with the invention is its enhanced apparent solubility rate. As indicative of the improvement in this respect, an unfilled milled flake soap, such as recommended for washing woolens and fine clothing, was compared with identical soap in which 5% by weight of guanidine stearate has been incorporated The-following table shows the relative apparent solubility as .determined'lat difierent temperatures by standard Washability laboratory tests: a

Tab e 1 r Apparent Complete Solubility Rate Temperature U Same Soap Cona fi gg gg taming 5% by m 3 We ght Guan d ne Stearate 90 F; .l 35 29 sec. jj F 7 min 2min. 75 F. Not in 10 min..- 3% min.

1 Contains potoshsoap. 7 This improvement in solubility'is indeed surprising because guanidine stearate itself is not appreciably soluble except in water much hotter than ,F. I i

While improved solubilityof soapscan be obtained by the inclusion of a larger amountof po-' tassium soaps and by the use of softer =oils, i. .e.,- glyoerides of unsaturated fatty acids or saturated fatty acids of lower molecular weights; it-is often undesirable for economic reasons to resort tothese ingredients in :a soap product. The ability to obtain enhanced solubility by the inclusion .ofi guan idine stearate appears to surpass'the solubilizing effect of potash soaps to a striking exten as can be seen from the aboyetable. r

' Another property of thessoap product of the invention is its superior detergent action as'reflected in-its property of accomplishing a larger amount of washing with a given amount of soap product. This may be demonstrated by a stand" ard dishwashing test in which standardizedsoilei plates are washed in watercontaining a given amount of the soap product, and the number of such soiled plates that may be washed before the water loses its detergent or' washing action is determined. A comparison of the same regular unfil ed milled cakeso p Produ t with h s me product-cont ining, by e shtguam ine stee ate awo dance w th h invention, is. sh w in he iol o ingf table:

Table II I Number of Soiled Plates Washed g i g g Same soap Conq 0 Regular Untaining'5'7 by i Water filled Milled weight Soap Flakes Guanidine Stearate From the above table it will be seen that the numher of plates that may be washed withthe soap product of the invention is materially greater than can be washed with an ordinary soap.

Although somewhat similar results could be obtained by including a builder, such as tetra.-

sodium pyrophosphate, the use of 'guanidine in milled flakes, whereas the use of an inorganic salt, such as a phosphate, tends to make the soap short, so that themilling operation is more difllcult and the resulting flakes are more brittle and tend to break or dust more readily.

Another advantage of a soap containing guanidine is its mildness in comparison with its detergency. While this detergency can be obtained with inorganic soap builders, such as the phosphates, it is generally conceded that the presence of such builders increases the irritating effect upon more sensitive skins. The mildness oi the guanidine stearate soap is indeed surprising since guanidine itself is a strong base.

A soap product containing guanidine stearate in accordance with the invention has the additional advantage in that less scum or sediment is formed with hard water, particularly in a rinsing operation. Under these conditions the presence of the guanidine'stearate helps to maintain the insoluble calcium and magnesium soaps in a dispersed state and minimizes scum.

The unique characteristic of the guanidine stearate-containing soap is also confirmed by the fact that guanidine laurate and guanidine myristate, while about equal in sudsing and detergent properties to the corresponding sodium laurate and sodium myristate have: little effect in improviding the properties of ordinary soap. This may be seen from the following table in which soiled plates were washed in the same manner as that described previously except that'the soaps contained guanidine laurate and guanidine myristate respectively instead of guanicline stearate:

From the above table it will be seen that the guanidine laurate and myristate do not improve the detergent properties. This might be expected in view of the known properties of the guanidine laurate and myristate when used alone. The stearate, however, is so insoluble as to be o f little use by'itself. The fact thatit would improve the properties of'ordinary soaps is a result entirely unexpected and unpredictable from the action of guanidine stearate alone.

The soap product containing the guanidiine stearate may be in any form, such as cake or bar. form, in flake form, or as a powder, spray dried particles, threads, ribbons, sheets, and other .forms.

In general, the improved properties are not so noticeable in a filled or built soap. The presence of the inorganic electrolyte builders in these soap 7 products is believed to interfere somewhat with the action of the guanidine stearate in the soap product.

The invention assumes particular importance in connection with improving the properties of an all-soap product of the unfilled and unbuilt type, especially when in flake form, Where mildness is a desirable property both with reference to the materials being washed and the skin of the-user, but which soap nevertheless is to be readily soluble and possess an enhanced detergent action;

It will be obvious that the invention includes many variations in the manner in which the guanidine' stearate may be incorporated in the soap and the form and constitution of the soap product. All such variations are obvious to those skilled in the art of making soap and are intended to be included within the invention if they fall within the following claims.

'I claim:

1. A solid, all-soap product for washing with Water, consisting essentially of an unfilled alkali metal soap and l to 15% by weight of guanidine stearate.

- 21 An unfilled, milled, white soap product in flake form for washing witlrwater, consisting essentially of an alkali metal soap uniformly admixed with 1 to 15% by weight of guanidine stearate.

i 3. An unfilled, milled, white soap product in flake form for washing with water, consisting essentially of an alkali metal soap uniformly admixed with about 5% by weight of gua'nidine' stearate. 1

LLOYD F. HENDERSON.

' REFERENCES CITED The lollowing references are of record in the file'of this patent:

UNITED STATES PATENTS Number Name Date 1,833,899 Hoyt Dec. 1, 1931 2,284,086 Ericks May 26, 1942 OTHER REFERENCES Uses and Applications of Chemicals and Related'Materials, Gregory (1944), page 159.-

American Soap Makers Guide, Stanislaus'and Meerbott (1928), page 618.

Modern Soap and Detergent Industry, Martin (1931), vol. 1, sec. 1, page 11. 

